Department of Applied Physics, Aalto University, Aalto, Finland.
Department of Physics and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland.
Nature. 2018 Apr;556(7702):478-482. doi: 10.1038/s41586-018-0038-x. Epub 2018 Apr 25.
Quantum entanglement is a phenomenon whereby systems cannot be described independently of each other, even though they may be separated by an arbitrarily large distance . Entanglement has a solid theoretical and experimental foundation and is the key resource behind many emerging quantum technologies, including quantum computation, cryptography and metrology. Entanglement has been demonstrated for microscopic-scale systems, such as those involving photons, ions and electron spins , and more recently in microwave and electromechanical devices. For macroscopic-scale objects, however, it is very vulnerable to environmental disturbances, and the creation and verification of entanglement of the centre-of-mass motion of macroscopic-scale objects remains an outstanding goal. Here we report such an experimental demonstration, with the moving bodies being two massive micromechanical oscillators, each composed of about 10 atoms, coupled to a microwave-frequency electromagnetic cavity that is used to create and stabilize the entanglement of their centre-of-mass motion. We infer the existence of entanglement in the steady state by combining measurements of correlated mechanical fluctuations with an analysis of the microwaves emitted from the cavity. Our work qualitatively extends the range of entangled physical systems and has implications for quantum information processing, precision measurements and tests of the limits of quantum mechanics.
量子纠缠是一种现象，即系统之间不能独立描述，即使它们可能被任意大的距离隔开。纠缠有坚实的理论和实验基础，是许多新兴量子技术的关键资源，包括量子计算、密码学和计量学。纠缠已经在微观尺度系统中得到了证明，例如涉及光子、离子和电子自旋的系统，以及最近在微波和机电设备中。然而，对于宏观尺度的物体，它非常容易受到环境干扰，并且宏观尺度物体的质心运动的纠缠的产生和验证仍然是一个悬而未决的目标。在这里，我们报告了这样一个实验演示，移动体是两个质量较大的微机械振荡器，每个振荡器由大约 10 个原子组成，与一个微波频率的电磁腔耦合，用于创建和稳定它们的质心运动的纠缠。我们通过将对相关机械波动的测量与对腔发射的微波的分析相结合，推断出在稳态下存在纠缠。我们的工作从质量上扩展了纠缠物理系统的范围，并对量子信息处理、精密测量和量子力学极限的测试具有重要意义。
